1. Field of the Invention
The present invention relates to a Stirling engine.
2. Description of the Related
Stirling engines use, as a working gas, helium, hydrogen, or nitrogen instead of chlorofluorocarbons. It is for this reason that a Stirling engine has been receiving increasing attention as a heat engine that does not destroy the ozone layer. Examples of the Stirling engine are disclosed in Patent Documents 1 and 2.
It is a piston and a displacer that play an important role in the Stirling engine. The piston is made to reciprocate by a power source such as a linear motor, and the displacer reciprocates with a predetermined phase difference relative to the piston in synchronism therewith. The piston and the displacer make the working gas circulate between a compression space and an expansion space, thereby forming a reverse-Stirling cycle. In the compression space, the temperature of the working gas is increased by isothermal compression; in the expansion space, the temperature of the working gas is reduced by isothermal expansion. As a result, the temperature in the compression space is increased, and the temperature in the expansion space is reduced. Dissipation of heat from the compression space (the high-temperature space) through a high-temperature heat-transfer head makes it possible for the expansion space (the low-temperature space) to absorb external heat through a low-temperature heat-transfer head. This principle allows the Stirling engine to be used as a refrigerating engine.
Patent Document 1: JP-A-2004-052866 (pages 5 to 6, FIG. 1)
Patent Document 2: JP-A-2003-075005 (pages 3 to 6, FIG. 2)